Catheter based balloon for therapy modification and positioning of tissue

ABSTRACT

An apparatus and method for shielding non-target tissues and organs during thermotherapy, brachytherapy or other treatment of a diseased target tissue. The apparatus includes a catheter shaft having input and output lumens and at least one inflatable balloon. A plurality of input lumens within the catheter shaft allows the passage of liquid or gas through an input port and into the interior of the balloon thereby inflating the balloon. The gas or liquid can then be cycled through the inflated balloon through an output port and output lumen and out of the catheter shaft. Temperature sensors or other sensors may be attached to the balloon or catheter to monitor temperature or other conditions at the treatment site. The catheter is positioned between the target tissue or organ and sensitive non-target tissues in proximity to the target tissue and inflated causing a physical separation of tissues as well as a physical shield.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 10/756,588filed on Jan. 12, 2004, now U.S. Pat. No. ______, incorporated herein byreference in its entirety, which is a divisional of U.S. applicationSer. No. 10/020,583 filed on Dec. 14, 2001, now U.S. Pat. No. 6,746,465,incorporated herein by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not Applicable

NOTICE OF MATERIAL SUBJECT TO COPYRIGHT PROTECTION

A portion of the material in this patent document is subject tocopyright protection under the copyright laws of the United States andof other countries. The owner of the copyright rights has no objectionto the facsimile reproduction by anyone of the patent document or thepatent disclosure, as it appears in the United States Patent andTrademark Office publicly available file or records, but otherwisereserves all copyright rights whatsoever. The copyright owner does nothereby waive any of its rights to have this patent document maintainedin secrecy, including without limitation its rights pursuant to 37C.F.R. § 1.14.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention pertains generally to devices that assist with internaldiagnostic imaging and treatment procedures, and more particularly to acatheter based balloon for temperature, acoustical and radiologicalblocking as well as the repositioning of treated and sensitive tissues.

2. Description of Related Art

Conventional hyperthermia or tissue heating at moderate temperatures(41° C. to 45° C.) has been shown to promote changes in cellulardynamics, tumor microcirculation, and blood vessel permeability that canbe exploited to enhance other therapies such as radiation andchemotherapy for cancer treatment, drug delivery and potentiation, genetherapy, and even organ preservation.

The immediate physiological effects of thermal exposure during thermaltherapies include heat-induced acceleration of metabolism, thermalinactivation of enzymes, and the rupture of cell membranes. Delayedeffects of thermal exposure include intracellular and tissue edema,hyperemia with increasing blood flow, as well as an increase in bloodvessel permeability and dilatation.

The damage due to thermal effects alone is reversible for thermalexposures at lower temperatures with relatively shorter times ofexposure (non-lethal thermal doses). For exposures at comparativelylonger times or higher temperatures, cellular repair mechanisms can nolonger keep up or lose function due to the thermal damage of keyenzymes, and cell death and tissue necrosis will occur within 3 to 5days. Different tissues exhibit different levels of sensitivity tothermal damage.

The localization of exposure of high-temperature hyperthermia attemperatures greater than 45° C. to 50° C. can be used to selectivelydestroy or permanently alter tissue regions. In the high-temperatureregime, thermal coagulation and thermal necrosis occurs in tissuesexposed to temperatures greater than 50° C. to 55° C. for a duration of1 to 2 minutes or shorter times at even higher temperatures. The thermalexposure of tissues to high temperatures causes many cellular and tissuestructural proteins to undergo irreversible denaturation andconformational changes. These thermal effects are lethal and immediate,producing thermally coagulated (dead) tissue.

On the extreme end, temperatures close to or greater than 100° C.generate less subtle effects, such as explosive vaporization andablation of tissue. Varying degrees of high temperature thermal therapyare used for cancer therapy, treatment of cardiac arrhythmias, treatmentof benign disease (BPH, uterine and breast fibroids), snoring, cosmesis,tissue modification, treatment of sports injuries, etc. However, theefficacy of these treatment modalities may be limited due to inadequacyin protecting sensitive non-targeted tissues or adequately treating alarge enough of a volume of tissue.

One example of an organ that responds well to various forms of thermaltherapy is the prostate gland. Benign prostatic hyperplasia (BPH) is afrequent benign disease that often requires surgical intervention.Prostate cancer affects 250,000 men annually. Surgery and radiationtherapy are the common forms of treatment for prostate cancer. Numerousbiological and clinical investigations have demonstrated that heattreatments within the 41° C. to 45° C. range can significantly enhanceclinical responses to radiation therapy, and has the potential forenhancing other therapies such as chemotherapy, immunotherapy, and genetherapy as well.

Furthermore, high temperature hyperthermia (greater than 50° C.) alonemay be used for selective tissue destruction as an alternative toconventional invasive surgery (Transurethral Resection, or TURP).Thermal techniques can also be utilized to complement existing coursesof treatment or provide a minimally invasive alternative to surgery withless complications, and morbidity for each of these diseases.Additionally, transurethral, transrectal, and interstitial systems thatuse RF currents, lasers, microwaves, ultrasound, and thermal conductionheating technology, can be implemented in the clinic or underdevelopment for this type of therapy.

Presently, treating the prostate gland with heat is problematic. Themost significant clinical experience to date includes treatment of BPHwith transurethral microwave devices. If properly positioned within theprostatic urethra, these devices can thermally destroy a region withinthe center of the prostate, which leads to a reduction of BPH symptoms.Improvements to these devices and clinical protocols are directedtowards decreasing treatment time and destroying larger amounts oftissue in a more precise manner. Although moderately effective fortreatment of BPH, these devices are not effective for treating prostatecancer, which mostly involves tissues away from the urethra in theposterior portion of the gland, often adjacent to critical nerves andthe rectum. In order to treat large distances from the urethra, higheramounts of energy and greater temperatures are required, leading todamage of the rectum or surrounding non-targeted tissues. Precisetechniques for localizing or depositing energy within the gland arerequired for the treatment of cancer. Transrectal focused ultrasounddevices (HIFU) offer some spatial control but treating the most dorsalportion of the prostate is still problematic, due to the risk of thermaldamage to the rectum. New developments in transurethral ultrasoundheating technology have demonstrated precise, directed and extensiveheating capabilities in the anterior and lateral prostate tissue. Largevolumes of tissue can be heated in the posterior margin of the prostategland, but extreme care needs to be undertaken to avoid damage to therectum and other non-target tissues. The potential exists to heat theentire prostate with transurethral ultrasound if the rectum tissue canbe protected and incident energy can be reflected back to the prostate.Interstitial approaches (needle implantation) provide another method oflocalizing heating energy, but only interstitial ultrasound has thecapability of directional heating patterns to avoid the rectum andsurrounding bone.

A second example of effective thermal therapy is in the treatment ofgynecological diseases. Gynecological diseases treated by thermaltherapy typically include menorrhagia, uterine and cervical cancer, anduterine fibroids. In the case of menorrhagia, different heatingmodalities are placed directly within the os of the uterus and heatingenergy is applied. For fibroids, interstitial lasers and RF energy havebeen applied to thermally destroy the tissues. New developments inultrasound heating technology are also leading to external,intracavitary, and interstitial techniques that promise betterlocalization. The amount of heating power, temperature distributions,and applicator placement are often limited in the treatment of thesediseases by the need to protect sensitive non-targeted tissues.

Thus it can be seen that the usefulness and efficacy of thermaltherapies are limited by the sensitivity to thermal exposure ofassociated non-target tissues. The usefulness and efficacy of treatmentsother than thermal therapy, such as interstitial and external beamradiation therapies, may also be limited by the collateral damage tonon-target tissues that can occur with these therapies.

Some other cancer therapies include the placement of small radiationsources into the tumor using specialized catheters in a procedure calledbrachytherapy. For example, low dose rate brachytherapy (LDR) includesthe permanent implantation of radioactive “seeds” of gold or iodine intothe tumor or organ tissues. The implanted seeds give off radiation inlow doses over a period of several months and remain in the organpermanently. A typical LDR brachytherapy procedure for prostate cancermay include the placement of over 100 radioactive implants in theprostate gland of the patient.

A second brachytherapy procedure was developed, known as high dose ratebrachytherapy (HDR), which uses precisely positioned catheters at tumorsites. High dose radiation sources are then sent to the tumor sitesthrough the catheters and removed from the body after a period of timeand are temporary implants. Thus, a high dose of radiation can bedirected to the cancerous tumor for a time and removed. However, properplacement of the HDR catheters is critical because of the high dosagesof radiation involved.

Prostate adenocarcinomas for example, are particularly well suited forboth LDR and HDR brachytherapy procedures. The three dimensionalvisualization of the placement of 125-Iodide seeds duringtransperperineal implantation, for example, has recently beenaccomplished with the use of transrectal ultrasonography (“TRUS”).Unfortunately, the imprecise placement of radiation sources can stilloccur with the use of ultrasound due to the proximity of the bladder andrectum and associated structures to the prostate gland. For both ofthese forms of interstitial radiation therapy, computer treatmentplanning is performed to produce a specific radiation dose distributionencompassing the target regions, and includes a safety margin aroundsensitive structures such as the rectum. For many cases, especiallytreatment of a previously radiated recurrence, the total radiation dosethat can be applied is limited due to the exposure limits on normaltissue structures that are close to the prostate gland such as therectum, bladder and urethra. For prostate and uterine tissue, thistranslates to a limited radiation treatment in the posterior portion ofthe organ in proximity to the rectum.

Accordingly, there is a continuing need in the art for a device orprocedure that can apply thermal or radiation therapy to the targettissue or tumor while insulating or positioning associated sensitivestructures to modify exposure to radiation or thermal treatments andenhancing diagnostic imaging. The present invention satisfies theseneeds, as well as others, and generally overcomes the deficiencies foundin existing equipment and methods.

BRIEF SUMMARY OF THE INVENTION

The present invention generally comprises a catheter with one or moresmall deployable balloons, bladders, or expandable membranes that may beinserted into the body using common implant techniques known in the art.By way of example, and not of limitation, in accordance with one aspectof the invention, a catheter having a central lumen is provided with aballoon attached to the catheter shaft and the interior of the balloonis in fluid communication with the central lumen. In one embodiment, asecond lumen in the catheter provides a conduit for an electricalconnection to a number of temperature sensors disposed in or on theballoon. The temperature sensors provide a general indication of thethermal exposure of tissues and structures surrounding the targettissues. In another embodiment the temperature sensors indicate thelocal temperature of the target tissue during treatment. In anotherembodiment the sensors detect localized radiation exposure.

The balloons may be provided in various predetermined shapes and pointsof adhesion to the catheter and may be folded prior to insertiondepending on the procedure. Gas or liquid is then introduced through oneof the central lumen (s) and into the balloon thereby inflating theballoon after placement of the catheter in the body.

In an alternative embodiment, the catheter has an input lumen(s) and anoutput lumen(s) that have input and output ports to and from theinterior of the balloons. Fluid introduced to the input lumen enters theinterior of a balloon through the input port causing it to inflate. Thefluid in the balloon can be cycled by removing fluid from the balloonthrough the output port and output lumen. With this embodiment, a gascan be initially introduced to the balloon and then later a liquid canbe cycled through the system replacing the gas. Also depending upon theprocedure, gas can be interchanged for the fluid, or varying levels ofgas and fluid can reside within same device or balloon or compartment.One medium can also be used to purge the other.

In another embodiment, multiple balloons may be positioned on thecatheter and are connected with a common lumen so that the balloonsinflate simultaneously when a fluid or gas is introduced into the inputlumen. In another embodiment, the catheter has multiple balloons with aseparate controlling set of communication lumens associated with eachballoon. In this embodiment, each balloon may be independently filledwith different material at different levels of inflation at differenttimes as needed.

In an embodiment configured for use with treatment of the prostate, thecatheter is inserted in the space between the prostate and the rectumand then inflated. The placement of multiple catheters can also beapplied as part of this treatment. Inflation of the balloon(s)physically separates the thermal and radiation sensitive rectum tissuefrom the prostate gland being treated, and thereby providing a level ofthermal insulation. The fluid filled balloon may act as a heat sink todraw heat away from the sensitive tissues. The fluid may also beintroduced at a temperature below the temperature of the body of thepatient.

The fluid filled balloon may also act as a radiation absorber ortransmitter to reduce or modify exposure to the sensitive tissues. Also,the gas or fluid inflating the balloon may act as an acoustic insulatoror the fluid may act as an acoustic conductor as desired duringdiagnostic and treatment stages of the underlying procedure.

In one embodiment, either a gas or a fluid with an acoustic mismatchfrom surrounding tissue or an acoustic absorber is used to inflate theballoon(s) and thereby modify the acoustic transmission and reflectivecharacteristics between the tissue and the device.

In another embodiment, membrane material and fluid is selected forlevels of electromagnetic mismatch from tissue or electromagneticabsorber is filled in balloon(s) to modify the electromagnetictransmission and reflective characteristics between tissue and device.

In yet another embodiment, membrane material and fluid is selected forlevels of electrical impedance mismatch from tissue or electricallyconductive or resistive material is filled in balloon(s) to modify theelectrical transmission characteristics between tissue and device.

In still another embodiment configured for use with HDR brachytherapyprocedures, one or more catheters are placed between the target organand the organs or structures in proximity to the target tissue. Theballoon is inflated with a gas or fluid to physically position orseparate the organs or tissues and thereby modify the exposure ofsurrounding structures during treatment of the target tissue. The fluidcan be of the type to transmit or absorb radiation.

In another embodiment, the interior of the balloon has a partitionseparating the interior of the balloon into two chambers. One chambermay be filled with a liquid and the other chamber filled with a gas inthis embodiment.

The catheter material may be hard or soft or rigid or flexible dependingon the desired application. The tip of the stiff catheter may be sharpto allow for the direct insertion into tissue. The catheter tip may alsobe blunt and may be configured for placement with a removable stiffeneror introducer. Flexible material such as silicone will allow for alonger duration implantation and longer balloon deployment such as withpermanent seed implant.

An object of the invention is to provide an apparatus and method ofthermally insulating organs and tissues from the target tissue of athermal therapy procedure.

Another object of the invention is to provide an apparatus and method ofinsulating organs and tissues from the target tissue of an externalradiology or brachytherapy procedure.

Another object of the invention is to provide an apparatus and method ofblocking the exposure of sensitive surrounding tissues to acousticenergy from the target tissue.

Another object of the invention is to provide a catheter that has one ormore deployable balloons with one or more lumens that have varied shapesand sizes that can conform to natural spaces or expand to apredetermined shape between internal body organs or tissues.

Still another object of the invention is to provide a catheter that hasa variety of sensors that can allow the monitoring of temperature,radiation dose or other localized conditions.

Another object of the invention is to provide an apparatus that canprovide fluid to inflate a balloon to selectively isolate targettissues.

Another object of the invention is to provide an apparatus that cancirculate fluid within the inflated balloon.

Further objects and advantages of the invention will be brought out inthe following portions of the specification, wherein the detaileddescription is for the purpose of fully disclosing preferred embodimentsof the invention without placing limitations thereon.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

The invention will be more fully understood by reference to thefollowing drawings which are for illustrative purposes only:

FIG. 1 is longitudinal cross-section of the distal tip section of oneembodiment of the catheter after inflation of the balloon in accordancewith the present invention.

FIG. 2 is transverse cross-section of the catheter shaft of theembodiment of the invention taken along the lines 2-2 shown in FIG. 1.

FIG. 3 is a longitudinal cross-section of an alternative embodiment ofthe catheter of the preset invention with intake and outtake lumens.

FIG. 4 is transverse cross-section of the catheter shaft of thealternative embodiment of the invention taken along the lines 4-4 shownin FIG. 3.

FIG. 5 is a longitudinal cross-section of an alternative embodiment ofthe catheter of the present invention showing two sets of intake andoutput ports.

FIG. 6 is a transverse cross-section of an alternative embodiment of thecatheter shown in FIG. 5.

FIG. 7 is a transverse cross-sectional view of an alternative embodimentof the catheter of the present invention.

FIG. 8 is a longitudinal cross-sectional view of an alternativeembodiment of the catheter of the present invention showing a balloonwithin a balloon and associated ports and lumens.

FIG. 9 is a front view of one embodiment of the invention positionedbetween the target tissue and a surrounding tissue.

FIG. 10 is a flow diagram showing generally the method steps in oneembodiment of a method for isolating a target tissue or organ fromsurrounding tissues or organs during treatment of the target organ.

DETAILED DESCRIPTION OF THE INVENTION

Referring more specifically to the drawings, for illustrative purposesthe present invention is embodied in the apparatus and methods generallyshown in FIG. 1 through FIG. 10. It will be appreciated that theapparatus may vary as to configuration and as to details of the parts,and that the methods may vary as to the specific steps and sequence,without departing from the basic concepts as disclosed herein.

Referring first to FIG. 1 and FIG. 2, the invention comprises apositioning catheter 10 with a catheter shaft 12 and tip 14 constructedfor insertion into the body of a patient. The catheter shaft 12 and tip14 may alternatively be configured to be inserted into tissue using aseparate needle introduction catheter that is removed after insertionand provides protection to the components of the device duringinsertion. The apparatus may be used interstitially as well aslaproscopically or endoscopically during procedures in the joints,abdomen, esophagus or uterus/cervix etc. The apparatus may be configuredfor short term or long-term placement in the body. The apparatus isparticularly suited to protect sensitive tissues or structures inproximity to target tissues for thermal or acoustic treatments.Additionally, the insertion of the catheter 10 and the balloon inflationmay be monitored using ultrasonic diagnostic imaging, CT fluoroscopicimaging, magnetic resonance imaging (MRI), or other appropriate meansfor visualization known in the art.

Catheter shaft 12 is preferably manufactured from polyethylene,polystyrene, polycarbonate, polyamide, silicone, rubber or similarflexible tubing. Alternatively, the catheter shaft 12 may be thin walledstainless steel hypodermic tubing or the like that provides anindependent structural support and integrity for direct insertion intotissue.

In the embodiment shown, the catheter shaft 12 has at least one centrallumen 16 running the length of the shaft 12 that allows the flow ofliquid or gas from the proximal end to the distal end of the catheter10. Fluid from the lumen 16 flows through ports 18 a, 18 b in the wallsof shaft 12 to the interior of balloon 20 thereby inflating balloon 20.Fluid may be introduced to lumen 16 of the proximal end of the cathetershaft 12 by a syringe or pump (not shown) that is connected and sealedto the catheter shaft 12. A syringe or pump that is capable ofdelivering a determined volume of gas or liquid at a desired pressure ispreferred to provide a consistent and predictable expansion of balloon20. The lumens may also be operably connected to valves known in the artto regulate the flow into and out of the catheter. In one embodiment,the shaft 12 may have a lumen that exits the tip of the shaft to allowthe introduction of medications or the like directly to the placementsite.

The fluid directed to balloon 20 is preferably non-toxic and nonreactive with the balloon or catheter material such as water, oil,diagnostic imaging agents or saline solution. Gases preferably used toinflate balloon 20 include air and perfluorocarbons or the like. Thefluid may also be a combination of liquid and gas.

Balloon 20 preferably comprises a flexible material such aspolyethylene, polyester, polyvinyl, Mylar, silicone, latex,polyurethane, C-flex or other appropriate material. The walls of balloon20 are preferably thin enough to collapse to a small volume around thecatheter shaft 12 for easy insertion yet durable enough to withstandrelatively high pressures upon inflation. In one embodiment, the balloonmaterial is a porous membrane that may allow movement of saline or othermaterial across the membrane and may conduct an electric current. Inanother embodiment, balloon 20 is made of an inelastic material thatwill inflate to a predetermined shape. That shape may be the shape ofthe target tissue, tissue space or organ. In yet another embodiment,balloon 20 has a metallized surface that is capable of conductingelectrical current. Balloon 20 may also be manufactured of material thatoptically blocks or is optically transparent to laser or infrared light.

It will be appreciated that the invention is not limited to aone-balloon configuration. If desired, more than one balloon may beaffixed circumferentially around shaft 12 with fluid ports communicatingwith the central lumen 16 to allow the simultaneous inflation of theballoons. Thus, a linear array of balloons can be used to raise andseparate tissues and organs during use.

Balloon 20 may also be configured to inflate to shapes that are lobed,spoon-shaped, generally planer, asymmetrical or any desired shape thatwill displace tissues or organs to the preferred positions, and providetreatment modification, protection, or thermal control. The size of theballoon 20 is also variable depending on the size of the organ to bedisplaced and the type of displacement required. Additionally, balloon20 may also be compartmentalized or chambered such that each chamber canbe inflated independently of the other and with different fluids.Balloon 20 may also be configured to have secondary balloons emanatingfrom a primary balloon or balloons.

Optionally, balloon 20 can have a number of miniature sensors 22 coupledto leads 24. The leads 24 are preferably disposed in a longitudinallumen 26 in the catheter shaft 12 and connect the sensors to appropriatemachines outside of the body. For example, sensors 22 may be miniaturethermocouples that can measure the temperature of the balloon, externaltissue or inflation liquid temperatures. Sensors 22 may also be capableof detecting radiation exposure or the like such as a TLD radiationdosimeter. Sensor 22 may also be a fiber optic sensor or a thermistor.Sensors 22 such as dosimeter chips may also be interpreted when thecatheter is removed from the body. Accordingly, the sensors 22 can beconfigured to measure the temperature of the target tissue, thenon-target tissue of the fluid media inflating the balloon 20 as well asradiation exposure.

Turning now to FIG. 3 and FIG. 4, an alternative embodiment of theinvention is shown. This embodiment is preferably configured tocirculate the fluid that inflates the balloon 20 under constant pressureso that the balloon 20 maintains its shape during fluid circulation.Changes in pressure of the inflation liquid may modify the shape of theballoon 20 through expansion or contraction in an embodiment with aballoon 20 made of elastic material. However, embodiments with balloons20 made of inelastic material may maintain the shape of balloon 20 withincreases in fluid pressure over the minimum pressure required toinflate the balloon 20.

In the embodiment shown, catheter 10 has a catheter shaft 12 that hastwo lumens 30, 38 running longitudinally the length of the shaft 12.Lumen 30 serves as an input lumen and is in fluid communication with oneor more input ports 32 that exit to the interior of balloon 20. Thus,gas or fluid passes through lumen 30 and port 32 into the interior 34 ofballoon 20 inflating the balloon.

The liquid or gas from the interior of the balloon 20 can be cycledthrough the interior 34 of the expanded balloon 20 through output port36 and into output lumen 38 and back to the proximal end of the catheter10. Valves (not shown) and other pressure regulation devices known inthe art can regulate the pressure of the liquid or gas entering andexiting a given set of lumens during circulation.

The use of input lumen 30 and output lumen 38 also allows the sequentialintroduction of different media to the balloon 20. For example, a fluidcan be first introduced during placement so that diagnostic imaging canbe used to verify balloon deployment. Next, an inert gas or air couldthen be introduced to lumen 30 to ports 32 to inflate balloon 20. Thegas in the balloon 20 can act as an acoustic barrier to ultrasonic wavesand provide acoustic isolation to the surrounding tissue. At the end ofthe procedure or when the sensors 22 indicate elevated tissuetemperatures, the gas in lumen 30 and balloon 20 can be flushed throughoutput port 36 and output lumen 38 by introducing water or oil or someother appropriate liquid into lumen 30. The liquid is preferablyintroduced to lumen 30 at the same pressure and volume as the gas sothat the balloon 20 does not deflate during the transition. The liquidcan act as a heat sink to draw the heat from sensitive tissues inphysical contact with the balloon 20 and/or transmission of acousticimaging or reduction of artifacts in diagnostic imaging. This processcan be repeated if necessary.

In one embodiment, the fluid is cycled in a closed loop at a controlledpressure with a pump (not shown) coupled between the intake lumen 30 andthe exit lumen 38. The pump is preferably capable of monitoring thepressure and volume of fluid introduced to the input lumen 30.

In another embodiment, the closed fluid loop has a cooling or heatingdevice that reduces or elevates the temperature of the liquid cyclingthrough the system and into lumen 30 and the balloon 20. Accordingly, inthe embodiment shown, the sensors 22 may monitor the temperature of theliquid at the balloon 20 or the temperature of the tissue and cool orheat the liquid to a specified temperature.

Referring now to FIG. 5 and FIG. 6 an alternative embodiment of thecatheter is shown. In this embodiment, the interior of the balloon isdivided into discreet sections by a partition 40. The partition 40creates two chambers 42, 44 within the balloon. While the embodimentshown has one partition, it will be understood that more than onepartition may be used. Each chamber 42, 44 are fed by a set of input andoutput lumens that permit selective inflation of the chamber and cyclingof fluid into the chamber. For example, a gas could be introduced intochamber 44 through input lumen 46 and input port 48 to inflate chamber44. The gas may be cycled through output port 50 and output lumen 52. Atthe same time or subsequently, chamber 42 may be filled with waterthrough input lumen 54 and input port 56. It can be seen the twodifferent types of media can be used to isolate target tissues fromsensitive non-target tissues. After the procedure, the chambers 42, 44of the balloon can be deflated by removing the contents of chamber 42through output port 58 and lumen 60 and the contents of chamber 44through output port 48 and lumen 46. Thus, the user of the catheter ofthe present invention can isolate non-target tissues from target tissueswith different media at different times during the course of thetreatment. Media that is particularly suitable for visualization of thecatheter for placement may be exchanged for media that is radio opaqueor acoustically opaque for use during treatment.

Turning now to FIG. 7, it can be seen that the balloon element of thecatheter can have a variety of configurations. The embodiment shown inFIG. 7 allows for inflation of the balloon to a generally planarconfiguration. Upon inflation, the central element 62 receives fluidfrom a central lumen 64. One or more conduits 70 connect the centralelement 62 to two adjoining chambers 66 a and 66 b that allow fluidcommunication from the central element 62 and inflate the chambers 66 a,66 b. There are one or more conduits 72 connecting chambers 66 a, 66 bwith 68 a, 68 b respectively such that the chambers are in fluidcommunication with each other. As seen in FIG. 7, the sequentialinflation of paired chambers can provide a planar separation of thetarget and non-target tissues as well as insulation of the tissues withthe use of appropriate fluid media to inflate the apparatus.

Another alternative embodiment of the apparatus having a balloon withina balloon configuration is shown in FIG. 8. In the embodiment shown,there is an outer balloon 78 that is attached to the shaft of thecatheter. Within the outer balloon 78 is an inner balloon 80. The outerballoon forms an outer chamber 82 and the inner balloon forms an innerchamber 84. The inner balloon 80 and the outer balloon 78 can beinflated independently of the other in the embodiment shown in FIG. 8.It can be seen that the inner balloon 80 can be inflated by theinsertion of fluid through input lumen and port 86 and cycled throughoutput port 88. Alternatively, ports 86 and 88 may be used as inputports and output ports simultaneously to inflate and deflate balloon 80.The outer balloon can be inflated by the insertion of fluid into theouter chamber 82 through the input lumen and port 90 and cycled throughoutput port 92. In this embodiment, for example, the catheter apparatuscould be placed at the desired location in the body and a gas introducedinto inner chamber 84 to facilitate acoustical imaging to insure properplacement. Outer balloon 78 may then be inflated by filling the outerchamber 82 with a fluid such as a diagnostic imaging agent that iscapable of insulating non-target tissues from various forms ofradiation. If desired, the gas in chamber 84 of inner balloon 80 can beexchanged for a chilled fluid such as water or oil that can be cycledthrough input port 86 and output port 88 to manipulate the localtemperature at the catheter balloon site.

Referring now to FIG. 9 and FIG. 10, the method for treatment 100 of adiseased tissue site utilizing the apparatus of the present inventioncan be illustrated with a specific exemplary condition, benign prostatehyperplasia. The first step 102 for treatment of the prostate afterdiagnosis and preparation for conventional surgical procedure is toinsert the catheter of the present invention into the body and locatethe virtual space between the target prostate gland and the structuresin proximity to the target gland. The prostate is located under thebladder and in front of the rectum. Visualization of the organs andstructures of the body and the catheter can be accomplished withultrasound, CT, fluoroscopic imaging or other imaging techniques knownin the art.

The second step 104 is to place the catheter 10 at the boundary of thetreatment site and the healthy tissue or sensitive tissues or structuresthat may be damaged during treatment of the target tissue. In theexample shown, the catheter 10 is placed in the virtual space betweenthe rectum and the prostate.

The third step 106 is to inflate the balloon member 20 to physicallydisplace the diseased target tissue and the surrounding critical tissuesor structures. The balloon 20 will physically displace the prostateorgan from the rectal wall in the example provided.

In many instances the separation that occurs between target andsensitive tissues need only be a few millimeters to effectively insulatethe sensitive tissues. The selection of the gas or liquid that inflatesthe balloon 20 as well as the size and number of balloons on thecatheter 10 will depend on the type of treatment that is to be performedon the target tissue. For example air or gas may be used to inflateballoon 20 to block or deflect acoustic energy directed toward sensitivetissues from the target organ or elsewhere. The placement and inflationof one embodiment of the catheter between the target tissue 74 such asthe prostate gland and the sensitive non-target tissue 76 such as therectum can be seen in FIG. 9.

The fourth step 108 is to initiate and complete the treatment on thetarget tissue once the target tissue is isolated from sensitive tissuesby the catheter assembly. Thermal therapy procedures of the prostategland may have radio frequency, laser, ultrasound, microwave or otherenergy sources to elevate the temperature of the prostate. In oneembodiment, the localized temperature of the target tissue and theproximal tissues is monitored during the procedure with temperaturesensors on the outside or inside of the balloon. Alternatively, thetemperature of the liquid within the balloon may be monitored.

In another embodiment, cycling thermally conductive fluid through thecatheter assembly and balloon 20 to draw off heat from the heatsensitive structures may reduce the temperature of the sensitivestructures. Alternatively, fluids with a temperature lower than bodytemperature can be cycled through the assembly 10 to quickly cool thestructures engaged with the balloon and catheter assembly 10.

In still another embodiment, during cryogenic treatments, the fluid thatis cycled within the catheter assembly 10 is preferably greater thanbody temperature. The pressure, temperature, volume and flow through theballoons 20 may be dynamically controlled during treatment.

The fifth step 110 is the deflation of balloon 20 and the removal of thecatheter assembly from the patient. In one embodiment, the fluid in thecatheter 10 is cycled and cooled to keep the temperature sensitiverectum at an appropriate temperature and to reduce the temperature ofthe target tissues after treatment.

Referring again to FIG. 10, a second example of the method for treatment100 of a diseased tissue site utilizing the apparatus of the presentinvention can be shown in treatment of prostate cancer using LDR seedimplants or HDR brachytherapy. After diagnosis, the insertion of thecatheter of the present invention into the body for placement into thespace between the target prostate tissue and the surrounding sensitivenon-target tissues is accomplished in step 102. The radioactive seeds orHDR brachytherapy catheters may be implanted before or after theplacement of the catheter in the body as provided in step 102.

Placement of the catheter at the boundary between the target andnon-target tissues in step 104 may be facilitated by the use ofultrasound, CT, fluoroscopic imaging or the like. The introduction ofsmall amounts of a radio-opaque or an acoustically opaque gas or liquidinto the catheter assembly may assist in the proper placement of thecatheter between target and non-target tissues.

The third step 106 is to inflate the balloon member to physicallydisplace the target tissue from the non-target tissues. In this example,the LDR seed implants are long term implants in the prostate exposingthe surrounding sensitive tissues such as the rectum to long-termexposure to radiation. Alternatively, the HDR brachytherapy implants areshorter term implants in the prostate exposing the surrounding sensitivetissues such as the rectum to high-doses of radiation. Accordingly, thecatheter 10 and balloon 20 are configured for permanent or long term orshort term placement. The balloon 20 may be filled with material thatwill provide a barrier to, or modification to, the radiation dose fromthe seed implants or direct radiation sources. The balloon 20 may alsobe shaped to reflect radiation back into the prostate gland or othertarget structure and away from surrounding tissues or move thesurrounding non-target tissue to a particular position.

The fourth step 108 is to initiate and complete treatment on the targettissue. The catheter and balloon apparatus may be kept in positionduring the majority of the LDR seed therapy or HDR brachytherapy toprotect the surrounding tissues as well as protect and shape the treatedtissues during therapy. In one embodiment, different media can be cycledthrough the balloon during diagnostic imaging and treatment.

Removal of the catheter after deflation of the balloon is accomplishedin the fifth method step 110. In the present example, the balloons maybe deflated by removing the gas or liquid media from the interior of theballoons. In one embodiment, the materials comprising the catheter andballoon are biologically inert and remain in the body permanently.

Accordingly, it will be seen that this invention provides a simple andeffective apparatus and method for isolating treated organs and tissuesfrom thermal or radiation sensitive tissues and structures fortreatment. Although the description above contains many specificities,these should not be construed as limiting the scope of the invention butas merely providing illustrations of some of the presently preferredembodiments of this invention. Therefore, it will be appreciated thatthe scope of the present invention fully encompasses other embodimentswhich may become obvious to those skilled in the art, and that the scopeof the present invention is accordingly to be limited by nothing otherthan the appended claims, in which reference to an element in thesingular is not intended to mean “one and only one” unless explicitly sostated, but rather “one or more.” All structural, chemical, andfunctional equivalents to the elements of the above-described preferredembodiment that are known to those of ordinary skill in the art areexpressly incorporated herein by reference and are intended to beencompassed by the present claims. Moreover, it is not necessary for adevice or method to address each and every problem sought to be solvedby the present invention, for it to be encompassed by the presentclaims. Furthermore, no element, component, or method step in thepresent disclosure is intended to be dedicated to the public regardlessof whether the element, component, or method step is explicitly recitedin the claims. No claim element herein is to be construed under theprovisions of 35 U.S.C. 112, sixth paragraph, unless the element isexpressly recited using the phrase “means for.”

1. An apparatus for minimally invasive therapy modification of tissue tobe treated, comprising: an elongated shaft having at least one lumenextending therethrough; and inflatable means coupled to an end of saidshaft for separating two distinct tissue regions and providingmodification of energy-based treatment delivered from an energy sourcelocated outside the target tissue and directed to the target tissue. 2.An apparatus according to claim 1, wherein said apparatus is configuredto be visualized for placement using imaging by at least one ofultrasound imaging, magnetic resonance imaging, computed tomographyimaging, and x-ray imaging.
 3. An apparatus for minimally invasivetherapy modification of tissue to be treated, comprising: an elongatedshaft having at least one lumen extending therethrough; and inflatablemeans coupled to an end of said shaft for separating two distinct tissueregions and providing modification of energy-based treatment deliveredfrom an energy source placed within the target tissue.
 4. An apparatusaccording to claim 3, wherein said apparatus is configured to bevisualized for placement using imaging by at least one of ultrasoundimaging, magnetic resonance imaging, computed tomography imaging, andx-ray imaging.
 5. An apparatus for minimally invasive therapymodification of benign or malignant tumor tissue to be treated in theuterus or cervical area, comprising: an elongated shaft having at leastone lumen extending therethrough; and an inflatable member coupled to anend of said shaft to separate at least one of two tissue regions; saidinflatable member configured to separate and isolate tissue to betreated from adjacent tissue to be protected during treatment.
 6. Anapparatus according to claim 5, wherein said apparatus is configured tobe visualized for placement using imaging by at least one of ultrasoundimaging, magnetic resonance imaging, computed tomography imaging, andx-ray imaging.
 7. An apparatus for minimally invasive therapymodification of tissue in skeletal joints to be treated, comprising: anelongated shaft having at least one lumen extending therethrough; and aninflatable member coupled to an end of said shaft to separate at leasttwo distinct regions; said inflatable member configured to separate andisolate tissue to be treated from adjacent tissue to be protected duringtreatment.
 8. An apparatus according to claim 7, wherein said apparatusis configured to be visualized for placement using imaging by at leastone of ultrasound imaging, magnetic resonance imaging, computedtomography imaging, and x-ray imaging.
 9. An apparatus for minimallyinvasive therapy modification of tissue to be treated in the abdomen,comprising: an elongated shaft having at least one lumen extendingtherethrough; and an inflatable member coupled to an end of said shaftto separate at least two distinct regions; said inflatable memberconfigured to separate and isolate tissue to be treated from adjacenttissue to be protected during treatment.
 10. An apparatus according toclaim 9, wherein said apparatus is configured to be visualized forplacement using imaging by at least one of ultrasound imaging, magneticresonance imaging, computed tomography imaging, and x-ray imaging.